Polyamide-imide polymers having fluorine-containing linking groups

ABSTRACT

The present invention provides novel heat stable polyamide-imide polymers having excellent flow properties which render them more readily processible into fibers, films, sheets and other molded articles. The polymers are prepared by forming the polycondensation product of one of more aromatic diamines, one or more trifunctional acid anhydride monomers, and one or more tetrafunctional aromatic dianhydrides, at least one of said monomers containing the groups ##STR1## linking two aromatic moieties, wherein R is CF 3  or phenyl. In addition to improved flow properties, the polyamide-imide polymers of this invention also exhibit improved solubility properties in most organic solvents, improved resistance to attack by chlorinated solvents such as trichloroethylene as compared with polyimides, improved hydrophobic properties as well as excellent thermal properties including resistance to thermooxidative degradation.

BACKGROUND OF THE INVENTION

This application is related to copending applications Ser. Nos. 316,254;316,342; and 316,380, all filed on even date herewith.

1. Field of the Invention

The present invention relates to aromatic polyamide-imide polymerscontaining the hexafluoroisopropylidine or the1-phenyl-2,2,2-trifluoroethane linking group having improved physicaland chemical properties, and to a method for preparing such polymers.

2. Description of Related Art

Polyamide-imide polymers and copolymers are known in the art. Thesematerials are generally prepared by the condensation polymerization oftrifunctional acid monomers such as the 4-acid chloride of trimelliticanhydride and one or more aromatic diamines. Examples of suchpolyamide-imide polymers are disclosed in U.S. Pat. Nos. 3,347,828,3,494,890, 3,661,832 and 3,920,612. These polymers may be characterizedby extremely good high temperature properties (Tg of about 275° C. orhigher), good high temperature stability, good tensile strength at hightemperatures, good mechanical properties and good chemical resistance.These polyamide-imides are useful as wire enamel coatings, laminates,molded products, films, fibers impregnating varnishes and in otherapplications where high thermal stability is required.

One of the problems associated with such polymers is that they exhibitgenerally poor flow properties which render them difficult to process,particularly to injection mold or to spin into fibers. These polymersare also relatively hydrophilic and tend to absorb moisture which caneffect their clarity, heat stability, processability, mechanical andelectrical properties.

Attempts have been made in the art to improve the flow properties ofpolyamide-imide polymers. For example, U.S. Pat. No. 4,448,925 disclosesincluding from about 1 to about 10 percent phthalic anhydride into thepolymerization recipe to provide polyamide-imide copolymers havingimproved flow properties. However, this technique for improving flowproperties is made at the expense of the heat stability and chemicalresistance of the polymer. Yet another method for improving the flowproperties of such polymers is to form blends thereof with up to about10% by weight of a polyamide such as nylon 6 or nylon 66, as disclosedin U.S. Pat. No. 4,575,924. Once again however, such an approach tosolving the flow problem is made at the expense of the thermal stabilityand optical clarity of the resultant polymer blend.

SUMMARY OF THE INVENTION

The present invention provides novel heat stable polyamide-imidepolymers having excellent flow properties which render them more readilyprocessible into fibers, films, sheets and other molded articles. Thepolymers are prepared by forming the polycondensation product of one ormore aromatic diamines, one more trifunctional acid anhydride monomers,and one or more tetrafunctional aromatic dianhydrides, at least one ofsaid monomers containing the groups ##STR2## linking two aromaticmoieties, wherein R is CF₃ or phenyl. In addition to improved flowproperties, the polyamide-imide polymers of this invention also exhibitimproved solubility properties in most organic solvents, improvedresistance to attack by chlorinated solvents such as trichloroethyleneas compared with polyimides, improved hydrophobic properties as well asexcellent thermal properties, including resistance to thermooxidativedegradation.

DETAILED DESCRIPTION OF THE INVENTION

The polyamide-imide polymers of the present invention may becharacterized as having structural units of the formula: ##STR3##wherein the terms (a) and (b) are equal to the mole fraction of eachrecurring unit in the polymer chain and (a) ranges from about 0.05 toabout 0.95, (b) ranges from about 0.05 to about 0.95, with the provisothat the sum of (a) and (b) is equal to 1.00, n is a number sufficientto give rise to a polyamide-imide inherent viscosity of at least about0.1 as measured from a solution of the polymer in dimethyl acetamide at25° C. at a polymer concentration of 0.5 weight percent, A is a divalentaromatic moiety, and B is a tetravalent aromatic moiety of the residuumformula: ##STR4## With respect to polyamide-imides of formula 1, B maybe the tetravalent residuum of either 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)-1-phenyl-2,2,2-trifluoroethane dianhydride, 1,1-bis[4-(3,4-dicarboxyphenyl)phenyl]-1-phenyl-2,2,2-trifluoroethane dianhydride, and4,4-bis[2-(3,4-dicarboxyphenyl) hexafluoroisopropyl] diphenyl etherdianhydride.

In the polyamide-imides of formula 1, A may be the divalent residuum ofone or a combination of aromatic diamines having the formula:

    NH.sub.2 --R--NH.sub.2                                     (4)

wherein R is the aromatic moiety of a phenylene, naphthalene, bis orpolyphenylene type compound. R is preferably selected from: ##STR5##wherein R' is a divalent moiety independently selected from a covalentcarbon to carbon bond, methylene, ethylene, propylene, isopropylene,hexafluoroisopropylidene, 1-phenyl-2,2,2-trifluoroethylidene, dichloroand difluoroalkylenes up to 3 carbons, oxy, thio, sulfinyl, sulfonyl,sulfonamido, carbonyl, oxydicarbonyl, oxydimethylene, sulfonyldioxy,carbonyldioxy, disilanylene, polysilanylene up to 8 Si atomsdisiloxanylene, and a polysiloxanylene up to 8 Si atoms. Preferably, thelinking group R' is selected from oxy, hexafluoroisopropylidene,1-phenyl-2,2,2-trifluoroethylidene, carbonyl, methylene, a covalentcarbon to carbon bond, disiloxanylene and polysiloxanylenes. Mostpreferably, R' is a carbon to carbon bond methylene,hexafluoroisopropylidene, 1-phenyl-2,2,2-trifluoroethylidene and oxy.

The hydrogen atoms of the aromatic groups A and/or B may be substitutedby one or more non-interfering monovalent substituents such as chloro,fluoro, lower alkyl or alkoxy having up to 6 carbon atoms, and phenyl.Also, the term "aromatic" as used herein is meant to includeheteroaromatics wherein one or more of the ring atoms is replaced with--O--, --S-- or --N-- atoms.

Divalent diamine monomers which may be used in preparing thepolyamide-imide copolymers of the present invention include:

m-phenylene diamine;

p-phenylene diamine;

1,3-bis(4-aminophenyl) propane;

2,2-bis(4-aminophenyl) propane;

4,4'-diamino-diphenyl methane;

1,2-bis(4-aminophenyl) ethane;

1,1-bis(4-aminophenyl) ethane;

2,2'-diamino-diethyl sulfide;

bis(4-aminophenyl) sulfide;

2,4'-diamino-diphenyl sulfide;

bis(3-aminophenyl)sulfone;

bis(4-aminophenyl) sulfone;

4,4'-diamino-dibenzyl sulfoxide;

bis(4-aminophenyl) ether;

bis(3-aminophenyl) ether;

bis(4-aminophenyl)diethyl silane;

bis(4-aminophenyl) diphenyl silane;

bis(4-aminophenyl) ethyl phosphine oxide;

bis(4-aminophenyl) phenyl phosphine oxide;

bis(4-aminophenyl)-N-phenylamine;

bis(4-aminophenyl)-N-methylamine;

1,2-diamino-naphthalene;

1,4-diamino-naphthalene;

1,5-diamino-naphthalene:

1,6-diamino-naphthalene;

1,7-diamino-naphthalene;

1,8-diamino-naphthalene;

2,3-diamino-naphthalene;

2,6-diamino-naphthalene;

1,4-diamino-2-methyl-naphthalene;

1,5-diamino-2-methyl-naphthalene;

1,3-diamino-2-phenyl-naphthalene;

4,4'-diamino-biphenyl;

3,3'-diamino-biphenyl;

3,3'-dichloro-4,4'-diamino-biphenyl;

3,3'-dimethyl-4,4'-diamino-biphenyl;

3,4'-dimethyl-4,4'-diamino-biphenyl;

3,3'-dimethoxy-4,4'-diamino-biphenyl;

4,4'-bis(4-aminophenoxy)-biphenyl;

2,4-diamino-toluene;

2,5-diamino-toluene;

2,6-diamino-toluene;

3,5-diamino-toluene;

1,3-diamino-2,5-dichloro-benzene;

1,4-diamino-2,5-dichloro-benzene;

1-methoxy-2,4-diamino-benzene;

1,4-diamino-2-methoxy-5-methyl-benzene;

1,4-diamino-2,3,5,6-tetramethyl-benzene;

1,4-bis(2-methyl-4-amino-pentyl)-benzene;

1,4-bis(1,1-dimethyl-5-amino-pentyl)-benzene;

1,4-bis(4-aminophenoxy)-benzene;

oxylylene diamine;

m-xylylene diamine;

p-xylylene diamine;

3,3'-diamino-benzophenone;

4,4'-diamino-benzophenone;

2,6-diamino-pyridine;

3,5-diamino-pyridine;

1,3-diamino-adamantane;

3,3'-diamino-1,1,1'-diadamantane;

N-(3-aminophenyl)-4-aminobenzamide;

4-aminophenyl-3-aminobenzoate:

2,2-bis(4-aminophenyl) hexafluoropropane;

2,2-bis(3-aminophenyl) hexafluoropropane;

2-(3-aminophenyl)-2-(4-aminophenyl) hexafluoropropane;

2,2-bis[4-(4-aminophenoxy)phenyl] hexafluoropropane;

2,2-bis[4-(2-chloro-4-aminophenoxy)phenyl] hexafluoropropane;

1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane;

1,1-bis[4-(4-aminophenoxy)phenyl]-1-phenyl-2,2,2-trifluoroethane;

1,4-bis(3-aminophenyl)buta-1-ene-3-yne;

1,3-bis(3-aminophenyl) hexafluoropropane;

1,5-bis(3-aminophenyl) decafluoropentane; and mixtures thereof.

In the preferred embodiments of the present invention, polyamide-imidesof formula 1 above are prepared by forming the polymer condensationproduct of a mixture of a mono-acid anhydride such as 4-trimellitoylanhydride chloride (4-TMAC) having the structure: ##STR6## and2,2-bis(3,4 dicarboxyphenyl) hexafluoropropane dianhydride(6F-Dianhydride) having the structure: ##STR7## with one or morearomatic diamines of the structure of formula 4 above.

Polyamide-imides of formula 1 above may also be prepared wherein thearomatic diamine monomer is 6F-Diamine or a mixture of 6F-Diamine and anon-fluorine containing aromatic diamine.

The polyamide-imide polymers of this invention may be based 100 mole %on fluorine-containing monomers as in the case of polymers of formula 1wherein both the A and B moieties are based on fluorine-containingresiduums of formula 2 or formula 3. More preferably, however, thepolymers contain from about 1 to about 100 mole percent of fluorinecontaining monomers and more particularly from about 2 to about 50 molepercent of fluorine containing monomers, based on the total weight ofacid/anhydride or dianhydride and amino monomers present in the polymer.

The acid/anhydride, dianhydride and diamine reactants, particularlythose containing fluorine, are preferably substantially electronicallypure and are referred to as electronic grade monomers. They generallyshould be at least about 98.5% pure, and more preferably at least about99.5% pure.

The polyamide-imides of the present invention are preferably prepared bya solution polymerization process, i.e., by reacting the acid anhydride,dianhydride and diamine monomers in an appropriate solvent, optionallyin the presence of a catalyst or an added inorganic salt such as lithiumchloride or calcium chloride, and in a nitrogen atmosphere.Polymerization is conducted under anhydrous, isothermal polymerizationconditions and preferably at a temperature of less than 35° C. Theintermediate polyamide-polyamic acid reaction product is then cyclizedto form the polyamide-imide either by chemical dehydration or by anappropriate heat treatment. The polymer may be recovered byprecipitation in water or an alcohol such as methanol, and washed.

The solvents useful in the solution polymerization process forsynthesizing the polyamide-imide compositions are the organic solventswhose functional groups do not react with the reactants to anyappreciable extent. In addition to being inert to the system, andpreferably, being a solvent for the polyamide-imide, the organic solventmust be a solvent for at least one of the reactants, preferably for allof the reactants. The normally liquid organic solvents of theN,N,dialkylcarboxylamide class are useful as solvents in the process.The preferred solvents are the lower molecular weight members of thisclass, particularly N,N-dimethylformamide and N,N-dimethylacetamide.Other useful solvents are N,N-diethylformamide, N,N-diethylacetamide,N,N-dimethylmethoxyacetamide, N-methyl caprolactam, and the like. Othersolvents which may be used include dimethylsulfoxide.N-methyl-2-pyrrolidone, tetramethyl urea, pyridine, dimethylsulfone,hexamethylphosphoramide, tetramethylene sulfone, formamide,N-methylformamide, butyrolactone and phenols such as m-cresol. Thesolvents can be used alone or in combinations.

To obtain the maximum inherent viscosity, i.e., maximum degree ofpolymerization, for any particular combination of monomers, solvent,etc., and thus produce shaped articles such as films and filaments ofoptimum toughness, it has been found that the temperature throughout thereaction should be maintained at 50° C., preferably below about 35° C.The degree of polymerization of the polyamide-imides is subject todeliberate control. The use of equimolar amounts of the reactants underthe prescribed conditions provides polyamide-imides of very highmolecular weight. The use of either reactant in large excess limits theextent of polymerization. In addition to using an excess of one reactantto limit the molecular weight of the polyamide-imides, a chainterminating agent such as phthalic anhydride may be used to "cap" theends of the polymer chains. Typical useful capping agents aremonoanhydrides or monoamines such as phthalic anhydride, aniline orp-methylaniline.

In the preparation of the polyamide-imides, it is desired that themolecular weight be such that the inherent viscosity of the polymer isat least about 0.1, more preferably from about 0.2 to about 1.0. Theinherent viscosity is measured at 25° C. at a concentration of 0.5% byweight of the polymer in a suitable solvent such as dimethylacetamide.

The quantity of organic solvent used in the process need only besufficient to dissolve enough of one reactant, preferably the diamine,to initiate the reaction of the diamine and the other monomers. It hasbeen found that the most successful results are obtained when thesolvent represents at least 60% of the final solution, that is, thesolution should contain 0.05-40% of the polymeric component, morepreferably 15 to 25%.

The second step of the process (dehydration) is performed by treatingthe polyamide-polyamic acid with a dehydrating agent alone or incombination with a tertiary amine such as acetic anhydride or an aceticanhydride-pyridine mixture. The ratio of acetic anhydride to pyridinecan vary from just above zero to infinite mixtures.

Tertiary amines having approximately the same activity as the preferredpyridine can be used in the process. These include isoquinoline,3,4-lutidine, 3,5-lutidine, 4-methyl pyridine, 3-methyl pyridine,4-isopropyl pyridine, N,N-dimethyl benzyl amine, 4-benzyl pyridine, andN,N-dimethyl dodecyl amine. These amines are generally used from 0.3 toequimolar amounts with that of the anhydride converting agent. Trimethylamine and triethlene diamines are much more reactive, and therefore aregenerally used in still smaller amounts. On the other hand, thefollowing operable amines are less reactive than pyridine:2-ethylpyridine, 2-methyl pyridine, triethyl amine, N-ethyl morpholine,N-methyl morpholine, diethyl cyclohexylamine, N,N-dimethylcyclohexylamine, 4-benzoyl pyridine, 2,4-lutidine, 2,6-lutidine and2,4,6-collidine, and are generally used in larger amounts.

An alternative method for the preparation of the polyamide-imides is thethermal dehydration of the intermediate polyamide-polyamic acid. Thistransformation is generally performed in bulk, preferably in the form ofa shaped article, e.g., film or filament of the polymamic acid. Thedehydration is conducted stepwise starting at temperatures of about 100°C. and increasing the temperature progressively to about 300° C. or evenhigher, depending on the particular case, towards the end of theimidization step. The reaction is preferably performed under an inertatmosphere, and atmospheric or reduced pressures can be employed.

The polyamide-imides of the present invention generally have a weightaverage molecular weight (M_(w)) within the range of from about 5,000 toabout 200,000 or more. The following examples are illustrative of theinvention:

EXAMPLE 1

This example details the preparation of a polyamide-imide having thestructure of formula 1 above and based on the reaction product of 0.10mole of methylene dianiline (MDA), 0.08 moles of 4-trimellitoylanhydride chloride (4-TMAC) and 0.02 moles of2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride(6F-Dianhydride) to yield a polyamide-imide containing about 20 molepercent 6F-Dianhydride, based on the total acid/anhydride monomercontent, or about 10 mole percent based on the totalacid/anhydride/diamine monomer content of the polymer.

A 1000 ml 4 neck flask, fitted with a stirrer, condenser, Y tube, powderaddition funnel, thermometer, dry ice-acetone cooling bath and nitrogenblanket was charged under nitrogen atmosphere with 19.8 grams (0.10moles) of MDA along with 208.0 grams of reagent grade dimethyl acetamide(DMAC). The mixture was stirred to dissolve the MDA and cooled down to atemperature of about -10° C. The 4-TMAC and 6F-Dianhydride wereseparately blended in a ratio of 16.84 g of 4-TMAC (0.08 moles) and 8.88grams of 6F-Dianhydride (0.02 moles) and 1/2 of this blend (12.86 grams)was gradually added to the solution of MDA in DMAC over a period ofabout 20 minutes time while continuing agitation and maintaining atemperature of about -5° C. under nitrogen atmosphere. The remainder ofthe 4-TMAC/6F-Dianhydride blend (12.86 grams) was then gradually addedover about 30 minutes time while continuing agitation at about -5° C.under nitrogen atmosphere. The beaker containing the blend was rinsedwith 25 grams of additional DMAC and this was also added to thepolymerization solution. The temperature of the solution was allowed torise to 5° C. and 11.0 grams (0.10 mole) of triethylamine was chargeddropwise over about 30 minutes time under nitrogen atmosphere whilecontinuing agitation. Thereafter, 25 grams of DMAC was charged undernitrogen and the reaction mass was agitated at a temperature within therange of 6°-10° C. for three hours. Thereafter, 37.8 grams of pyrridineand 54.2 grams of acetic anhydride was charged under nitrogen atmosphereand the reaction mass was then allowed to agitate for about 12 hours atroom temperature to complete cyclization. The reaction mass was thenfiltered to remove pyrridine hydrochloride. The polymer formed above wasprecipitated from solution in methanol by the addition of methanol tothe reaction liquor, that is by reverse precipitation, using about 2000ml of methanol for every 500 grams of polymeric solution. The resultingpolymer was then washed with water and methanol, and chopped to a finepowder as an aqueous suspension in a mechanical blender. The powder wasdried overnight in a vacuum oven at 60° C.

This polymer has the structural statistical formula: ##STR8##

EXAMPLE 2

This example sets forth the preparation of a polyamide-imide having thestructure of formula 1 above based on the reaction product of 0.1 molesMDA, 0.05 moles of 4-TMAC and 0.05 moles of 6F-Dianhydride to yield apolyamide-imide containing about 50 mole percent 6F-Dianhydride based onthe total acid/anhydride monomer content, or about 25 mole percent basedon the total acid/anhydride/diamine monomer content of the polymer.

The procedure of Example 1 was repeated but the following materials andquantities were employed:

MDA--19.8 grams

4-TMAC--10.5 grams

6F-Dianhydride--22.2 grams

DMAC--258.0 grams

pyridine--37.8 grams

Triethylamine--11.0 grams

Acetic Anhydride--54.2 grams

Polymerization was conducted and sequential addition of the abovereactants and materials and polymer recovery was as set forth inExample 1. 55.0 grams of a light yellow polymer in powdered form wasobtained.

EXAMPLE 3

This example sets forth the preparation of a polyamide-imide having thestructure of formula 1 above based on the reaction product of 0.2 molesMDA, 0.18 moles of 4-TMAC and 0.02 moles of 6F-Dianahydride to yield apolyamide-imide containing about 10 mole percent of 6F-Dianhydride basedon the total acid/anhydride monomer content, or about 5 mole percentbased on the total acid/anhydride/diamine monomer content of thepolymer.

The procedure of Example 1 was repeated but the following materials andquantities were employed:

MDA--39.6 grams

4-TMAC--37.9 grams

6F-Dianhydride--8.9 grams

DMAC--351.0 grams

Pyridine--75.6 grams

Triethylamine--22.0 grams

Acetic anhydride--108.4 grams

Polymerization was conducted and sequential addition of the abovereactants and materials and polymer recovery was as set forth in Example1.

73.2 grams of a light yellow polymer in powdered form was obtained.

EXAMPLE 4

This example sets forth the preparation of a polyamide-imide having thestructure of formula 1 above based on the reaction product of 0.25 molesof bis(4-aminophenyl) ether (ODA), 0.2 moles of 4-TMAC and 0.05 moles of6F-Dianhydride to yield a polyamide-imide polymer containing about 20mol percent of 6F-Dianhydride based on the total acid/anhydride monomercontent, or about 10 mole percent based on the totalacid/anhydride/diamine monomer content of the polymer.

The procedure of Example 1 was repeated, but the following materials andquantities were employed:

ODA--50.0 grams

4-TMAC--41.1 grams

6F-Dianhydride--22.2 grams

DMAC--1544.0 grams

Pyrridine--95.0 grams

Triethylamine--27.5 grams

Acetic anhydride--140.0 grams

Polymerization and sequential additions were conducted as set forth inExample 1 except that the amount of DMAC added to the reaction mixtureup to the point just after the addition of triethylamine was such as toyield a 10% by weight polymerization solution. 400 grams of the total1544 grams of DMAC was then added prior to the 3 hour polymerizationstep. The polymer was recovered as set forth in Example 1, yielding 96.5grams of bright yellow fluffy solids.

COMPARATIVE EXAMPLE 5

This example sets forth the preparation of a control polyamide-imide ofthe prior art which does not contain the fluorine-containing monomers.The control polymer is based on the reaction product of 0.12 moles ofMDA and 0.12 moles of 4-TMAC to yield a polyamide-imide of the prior arthaving the structure: ##STR9##

The procedure of Example 1 was repeated but the following materials andquantities were employed:

MDA--24.0 grams

4-TMAC--25.2 grams

DMAC--278.0 grams

Pyrridine--45.4 grams

Triethylamine--13.2 grams

Acetic anhydride--65.0 grams

Polymerization was conducted and sequential additions of the abovereactants and materials and polymer recovery was as set forth inExample 1. 42.5 grams of a light yellow polymer in powdered form wasobtained.

Properties of the polyamide-imide polymers prepared in accordance withExamples 1-5 appear in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    4-TMAC     6F-Dianhydride                                                                              Inherent                                                                           GPC           DSC TGA                                mole %                                                                              mole %  Diamines                                                                             Viscosity                                                                         Mw   Mn  Mw/Mn                                                                              Tg  5% wt. loss                   Example                                                                            (acid side)                                                                         (acid side)                                                                           mol % dl/gm                                                                              Mw   Mn  Mw/Mn                                                                              deg. C.                                                                           deg. C.                       __________________________________________________________________________    1    80    20      100 (MDA)                                                                           0.49 40500                                                                              21400                                                                             1.9  276 520                           2    50    50      100 (MDA)                                                                           0.68 64000                                                                              34900                                                                             1.8  298 500                           3    90    10      100 (MDA)                                                                           0.33 40000                                                                              21000                                                                             1.9  270 500                           4    80    20      100 (ODA)                                                                           1.37 167000                                                                             75800                                                                             2.2  300 490                           5 Control                                                                          100   0       100 (MDA)                                                                           0.33 41300                                                                              20700                                                                             2.0  271 510                           __________________________________________________________________________

The weight average molecular weight (M_(w)) and number average molecularweight (M_(n)) of the polymers described above were measured by gelpermeation chromatography (GPC) performed on dilute solutions of thepolymer in dimethylacetamide (DMAC). The actual apparatus employedconsisted of a Waters (Millipore Corp.) programmable automatic sampler,vacuum pump, chromatography columns with heater, and a differentialrefractometer connected to a Shimadzu CR 30A data reduction system withaccompanying software (version 1.1, Shimadzu part No. T/N 22301309-91).The refractometer used was a Waters model 410 and four chromatographycolumns, 500 Angstron, 1000 Angstron, 10,000 Angstron and 100,000Angstron (available from Waters) were connected in series. The systemwas calibrated using multiple available polystyrene standards ranging inmolecular weight as follows:

    ______________________________________                                        GPC CALIBRATlON                                                               Calibration Standard                                                          (Polystyrene)          Mol. Wt.                                               ______________________________________                                        1                      470,000                                                2                      170,000                                                3                      68,000                                                 4                      34,500                                                 5                      9,200                                                  6                      3,200                                                  7                      1,250                                                  ______________________________________                                    

The standards are essentially monodisperse, consisting substantially ofa single molecular weight. With the system thus calibrated the relative(relative to polystyrene standards) weight average molecular weightM_(w), the relative number average molecular weight M_(n), andpolydispersity (d), M_(w) /M_(n) were obtained for polymers produced inaccordance with the Examples given hereinabove.

Glass transition temperatures (Tg) were determined by differentialscanning calorimetry using a Perkin Elmer DSC-4 calorimeter operating at20° C./min., nitrogen atmosphere at 60 cc/min. Glass transitiontemperature by this method is generally defined as the point ofintersection of tangent lines about the point of first inflection of theheating curve of the polymer. Thermogravimetric analysis (TGA) wasperformed with a Perkin Elmer 65-2 analyzer at 20° C./min. with an airrate of 80 cc/min. TGA values given herein are for five percent weightloss; in other words, the temperature at which 5% weight loss isobserved is reported.

As is evident from the data in Table 1, the polyamide-imides of thepresent invention have Tg values essentially equivalent or higher thanthe control polyamide-imide of the prior art while at the same timeexhibiting improved flow properties and injection molding properties.Thus, the flow properties of the polymers of this invention are markedlyimproved without significant alteration of the glass transitiontemperature (Tg).

EXAMPLE 6

The flow properties of the polyamide-imides of this invention, thecontrol of Example 5, and a commercially available polyamide-imide soldby Amoco under its Trade Name Torlon® 4203L may be compared by formingcompression molded discs of each polymer type. Discs of approximately 1inch diameter were prepared using a hot press and piston cylinder moldto form the molded discs. Approximately 1/2 inch of polymer in powderform was sprinkled into the bottom of a mold piston and the piston wasinserted between the pallets of a hot press and heated to 300° C. Aftercoming to temperature, a pressure of 2000 psi was applied to the pistonfor 3 minutes. The pressure was then released, the mold cooled and themolded polymer disc having a thickness of about 20 mil was removed fromthe mold. Each of the polymers of Examples 1-4 produced a clear,transparent, yellow disc having good flexural properties. The controldisc of Example 5 was a non-transparent, compressed, fused yellow powderwhich was sintered in nature, indicative of poor flow and poor moldingproperties. The disc made from Torlon was in the form of compressed,fused yellow green pellets.

EXAMPLE 7

A calendered film of the polyamide-imide polymer prepared in Example 1was made by the following method. Two grams of the powdered polymer ofExample 1 was evenly spread on the surface of a dried 3 mil sheet ofKapton® polyimide polymer, available from the DuPont Company, andanother sheet of pre dried Kapton was placed over this to form asandwich. This sandwich structure was heated on a hot plate at 200° C.,and a metal plate heated to 250° C. was then placed on top of thesandwich structure. The structure was heated for 2 minutes under mild(50-100 psi) pressure to thoroughly dry the sample. The dried/heatedstructure was then passed between two rotating heated calender rollshaving a gap of 5 mils, the top roll being at a temperature of 348° C.and the bottom roll at 314° C. The roll pressure was 1500 psi. Thecalendered sample was cooled and peeled from the upper and lower sheetsof Kapton to yield a film having a thickness of 3.5 mil. This processwas repeated two more times.

The average tensile, modulus and % elongation of the three samples wereevaluated with the following results:

Tensile (K-PSI)--14.76

Modulus (M-PSI)--0.39

Elongation (%)--7.86

EXAMPLE 8

Melt spun fibers of the polyamide-imide polymer of Example 1 were madeby the following method. Approximately 10 grams of dried powderedpolymer prepared as in Example 1 was placed into the barrel of a onepiece cylindrical die and subjected to a cold-form pressure of 3000 psiusing a hydraulic press and a plunger. The resultant cold-formedcompressed rod was fed under pressure into a hot melt spinning machinewherein the polymer was subjected to temperatures in the range of about350° to 370° C., and extrusion pressures in the range of about 900 to4000 psi. The melt was passed through a filter and a spinnerette die andthe extruded fiber was taken up by a take up roller at speeds of 230 RPMand 690 RPM respectively. Four different fibers were prepared by thistechnique. The fiber properties and extrusion conditions are listed inTable 2.

                  TABLE 2                                                         ______________________________________                                        Spinnerette Conditions                                                                     Pres-         Tensile                                            Sam- Temp.   sure    Speed (GM/  Modulus                                                                              Elong.                                                                              Den-                            ple  (C)     (PSI)   (RPM) D)    (GM/D) (%)   ier                             ______________________________________                                        A    350     1,530   230   0.98  25.73  34.06 9.85                            B    360       900   230   0.87  25.74  38.91 7.17                            C    360     4,000   690   1.55  27.41  36.45 9.00                            D    370     1,100   690   0.62  23.25  31.10 7.97                            ______________________________________                                         *Speed (RPM): Take up speed of the meltspun fiber via a metal roller. (23     & 690 RPM equal 0.15 & 0.4 gm/min sample respectively.                   

The polyamide-imides of the present invention may be used in theirpreimidized form (polyamide-polyamic acid) as solutions in organicsolvent to produce films, coatings, composites and the like which may becured in-situ to form the polyamide-imide by the application of heat.

The polyamide-imides may be molded using techniques such as compressionmolding or injection molding to produce melt fabricated articles such asfibers, films, safety masks, windshields, electronic circuit substrates,airplane windows or the like. Shaping may be accomplished by subjectingthe polymer to temperatures of at least about 300° C. and pressure of atleast about 500 psi. They may be compounded with graphite, graphitefiber, molybdenum disulphide or PTFE for the production ofself-lubricating wear surfaces useful for piston rings, valve seats,bearings and seals. They may also be compounded with fibers such asglass, graphite or boron fibers to produce molding compounds for highstrength structural components such as jet engine components. Thepolyamide-imides may also be compounded with friction materials toproduce molding compounds for high temperature braking components orwith abrasive materials such as diamonds for high speed grinding wheels.

The polyamide-imides may be cast as films useful as wire and cablewraps, motor slot liners or flexible printed circuit substrates. Theymay be used as coatings on substrates such as aluminum or siliconedioxide. They are also useful to produce high temperature coatings formagnetic wire, dip coatings for various electronic components,protective coatings over glass, metal and plastic substrates, wearcoatings, and photoresist coatings useful in microelectronic processing.

The polyamide-imides may also be used to produce high temperatureadhesives for bonding aerospace structures or electrical circuitry,conductive adhesives when mixed with conductive fillers such as silveror gold for microelectronic applications, or adhesives for glass, metalor plastic substrates.

The polyamide-imides may also be used as varnish compositions or matrixresins to produce composites and laminates. The varnish compositions andmatrix resins may be used to impregnate glass or quartz cloth, orgraphite or boron fibers, for the production of radomes, printed circuitboards, radioactive waste containers, turbine blades, aerospacestructural components or other structural components requiring hightemperature performance, non-flammability and excellent electricalproperties.

In general, the polyamide-imides and polyamic-acid precursors of thisinvention may be used in all applications as disclosed in copendingapplication Ser. No. 124,704, filed in the U.S. Patent and TrademarkOffice on Nov. 24, 1987, the disclosure of which application isincorporated herein by reference.

It is to be understood that the above described embodiments of theinvention are illustrative only and that modifications throughout mayoccur to those skilled in the art. Accordingly, this invention is not tobe regarded as limited to the embodiments disclosed herein, but is to belimited as defined by the appended claims.

What is claimed is:
 1. A polyamide-imide polymer containing at least onerecurring structural unit of the formula: ##STR10## wherein the terms(a) and (b) are equal to the mole fraction of each recurring unit in thepolymer chain and (a) ranges from about 0.05 to about 0.95, (b) rangesfrom about 0.95 to about 0.05, with the proviso that the sum of (a) and(b) is equal to 1, n is a number sufficient to give rise to apolyamide-imide inherent viscosity of at least about 0.1 as measuredfrom a solution of the polymer in dimethylacetamide at 25° C. at apolymer concentration of 0.5 weight percent, A is a divalent aromaticmoiety, and B is a tetravalent aromatic moiety containing the ringsubstituted or ring unsubstituted residuum selected from: ##STR11## 2.The polymer of claim 1 prepared by the polycondensation polymerizationof a mixture of monoacid anhydride, dianhydride, and diamino monomers,at least one of said monomers being a fluorinated monomer selected fromthe group consisting of:2,2-bis(3,4-dicarboxyphenyl) hexafluoropropanedianhydride; 1,3-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride;1,1-bis(3,4-dicarboxyphenyl)-1-phenyl-2,2,2-trifluoroethane dianhydride;2,2-bis[4-3(3,4-dicarboxyphenoxy) phenyl] hexafluoropropane dianhydride;1,1-bis[4-(3,4-dicarboxyphenyl) phenyl]-1-phenyl-2,2,2-trifluoroethanedianhydride; 4,4-bis[2-(3,4-dicarboxyphenyl) hexafluoroisopropyl]diphenyl ether dianhydride; 2,2-bis(3-aminophenyl) hexafluoropropane;2,2-bis(4-aminophenyl) hexafluoropropane;2-(30aminophenyl)-2-(4-aminophenyl) hexafluoropropane; and the-1-phenyl-2,2,2-trifluoroethane homologues of such monomers.
 3. Thepolymer of claim 2 wherein said monoacid anhydride monomer is4-trimellitoyl anhydride chloride.
 4. The polymer of claim 2 whereinsaid fluorine containing monomer is 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride.
 5. The polymer of claim 2 wherein saidamino monomer is a diaryl diamine having the formula: ##STR12## whereinR' is a divalent moiety independently selected from a covalent carbon tocarbon bond, methylene, ethylene, propylene, isopropylene,hexafluoroisopropylidene, 1-phenyl-2,2,2-trifluoroethylidene, dichloroand difluoroalkylenes up to 3 carbons, oxy, thio, sulfinyl, sulfonyl,sulfonamido, carbonyl, oxydicarbonyl, oxydimethylene, sulfonyldioxy,carbonyldioxy, disilanylene, polysilanylene up to 8 Si atoms;disiloxanylene, and a polysiloxanylene up to 8 Si atoms.
 6. The polymerof claim 5 wherein R' is methylene.
 7. The polymer of claim 5 wherein R'is oxygen.
 8. The polymer of claim 5 wherein R' is ##STR13##
 9. Thepolymer of claim 2 containing from about 1 to about 100 mole percent offluorine-containing monomers.
 10. The polymer of claim 9 containing fromabout 2 to about 50 mole percent of fluorine-containing monomers.